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MITOSIS

Learn about the process of cell division known as mitosis, which is essential for growth and replication of cells in our body. Explore the three stages of the cell cycle - interphase, mitosis, and cytokinesis - and understand how DNA replication takes place. Discover the checkpoints that ensure proper cell division and learn about the consequences when these checkpoints fail, leading to conditions like cancer.

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MITOSIS

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  1. MITOSIS Cell division

  2. How do we grow? • In order to grow, our cells must replicate themselves. • You have approximately 1,600,000,000,000 skin cells! • Everyday you lose 1 million skin cells! Just look at the dust in your room 

  3. Boulengerula taitanus

  4. Cell Cycle • Every cell in your body goes through a cell cycle. Its like its own life mini life cycle. • What kinds of cells have to multiply throughout your life? • What kinds of cells usually stop multiplying as an adult?

  5. Cell Cycle • The life of a cell has 3 stages called the cell cycle: 1. Interphase 2. Mitosis 3. Cytokinesis

  6. Cell Cycle • One cell divides, and makes 2! TWINS!!!!

  7. 1. Interphase • It’s the longest phase • It is when the cells are carrying out functions to survive, and preparing for the second step, mitosis.

  8. Interphase • During interphase, cells increase in size • The cell makes proteins for survival • Some organelles duplicate! Why?

  9. Interphase • DNA replicates itself in interphase! • We have 3,000,000,000 nucleotide base pairs in our DNA that needs to be replicated! • How does DNA replicate?

  10. DNA Replication • 1. The strands unwind • 2. Each strand is a “parent” strand • 3. A new daughter strand attaches to each parent strand. • 4. You now have two copies of the DNA in one cell!

  11. DNA Replicated!-We now have double the amount of chromosomes in the nucleus!

  12. After DNA/chromosome replication • We are still in interphase!! • The cell makes extra organelles and proteins for the new cell  • The new cell is going to be called “daughter cells”

  13. P…M…A…T… 2. Mitosis • Mitosis has 4 stages: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase. REMEMBER PMAT

  14. Prophase Centromere Centrioles • Spindle fibres, attached to centrioles, form in the cell • DNA coils up tightly and forms X-shaped chromosomes • The spindle fibre attach to chromosome at a place called the centromere Spindle Fibres

  15. Metaphase • The spindle fibres pull the X-shaped chromosomes into a straight line in the middle of the cell.

  16. Anaphase • The spindle fibres begin to shorten • This pulls the centromeres apart • Each sister chromatid separates to an opposite end • Now there is one copy of the chromsomes at each end!

  17. Telophase • One set of chromosomes is now at each pole of the cell. • Spindle fibres begin to disappear! • Nucleolus appears • Nuclear membrane forms • Now you have two nuclei!

  18. 3. Cytokinesis • This is the last stage of the cell cycle! • It separates the two nuclei into two daughter cells. • Daughter cells are identical to the parent cell!

  19. Animal Cytokinesis The cell membrane pinches together to divide the cytoplasm and organelles.

  20. Plant Cytokinesis • Remember that plants have a tough cell wall!!!! • A cell plate forms along the centre of the cell to divide the cell.

  21. Checkpoints!!! • There are several checkpoints during the cell cycle to make sure things don’t go wrong! • Information is constantly being sent to the nucleus. The nucleus responds, telling the cell whether or not it should continue dividing.

  22. STOP!!! • Cells WILL NOT divide if… 1. There is not enough nutrients 2. DNA has not been replicated 3. DNA is damaged

  23. Cancer  • Some mutations in our DNA affect checkpoint proteins! • If there is no checkpoint, damaged cells that should be destroyed, will actually multiply! • CANCER is a number of disease that result from uncontrolled cell division.

  24. Cancer • Normal cells bump into their neighbors, who tell them to stop dividing. • Cancer cells do not listen to their neighbors, and continue to divide!

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